Former FBI Director James Comey, a longtime Republican who has clashed with U.S. President Donald Trump over the federal Russia probe, has doubled down on his earlier call for Americans to vote for Democrats in November congressional elections.

In a second tweet on the subject, Comey on Sunday wrote that Democrats should be wary of moving further to the political left in reaction to recent moves by Trump and the Republican Party.

"Democrats, please, please don't lose your minds and rush to the socialist left," he wrote on Twitter. "This president and his Republican Party are counting on you to do exactly that. America's great middle wants sensible, balanced, ethical leadership.